Split TEncodeContext and TDecodeContext

[CraigMacomber]

Description

Allow codecs to have distinct encode and decode context types, to allow for better management of id-compressor sessions, and other compression and session related inputs in the future.

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[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR updates the codec type system to allow different context types for encoding vs decoding, enabling future scenarios like distinct session/compression inputs on each side.

Changes:

• Split TContext into TEncodeContext and TDecodeContext across codec interfaces and version-dispatching codec builder types.
• Propagate the new context typing through versioned codec normalization/build paths.
• Add a test covering distinct encode/decode context typing.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
packages/dds/tree/src/test/codec/versioned/codec.spec.ts	Adds a regression test ensuring encode/decode can use distinct context types.
packages/dds/tree/src/codec/versioned/codec.ts	Refactors versioned codec builder/normalization types to support separate encode/decode contexts.
packages/dds/tree/src/codec/codec.ts	Updates core codec interfaces/utilities (IJsonCodec, ICodecFamily, withSchemaValidation, etc.) to support split contexts.

[daesunp]

Should we update TContext (line 175) in the doc comments now that it's TEncodeContext and TDecodeContext?

[daesunp]

Update TContext to TEncodeContext